The current sensor chip is the ACS712ELC-30A;

Pin 5V provides power supply; an on-board indicator shows power status;

The module can measure positive and negative 30 amps, with an analog output of 66mV/A.
With no test current, the output voltage is VCC/2;
PCB board size: 31 (mm) x 13 (mm);

Note: The ACS712 is based on the Hall effect; please avoid magnetic fields near this sensor.